The present invention pertains generally to medical devices, and more particularly to a catheter delivery system for endovascular stents and endovascular grafts.
The term xe2x80x9cstentxe2x80x9d is generally used to describe endoprosthetic devices which are implanted in blood vessels or other anatomical passageways of the body for the purpose of treating stenoses, aneurysms, occlusions, etc. Typically, such stents are implanted in blood vessels to maintain dilation and patency of an occluded region of blood vessel, or to bridge a weakened or aneurysmic region of blood vessel. On the other hand, some typical nonvascular applications of such stents are for the treatment of constrictions or injuries to the gastrointestinal tract (e.g., esophagus), ducts of the biliary tree (e.g., common bile duct) or anatomical passageways of the genitourinary tract (e.g., ureter, urethra fallopian tube, etc.).
Most stents are initially disposed in a compact configuration of relatively small diameter, whereby the stent may be mounted upon or within a delivery catheter for insertion and transluminal advancement into the desired anatomical passageway. Thereafter, such stents are radially expandable to a larger xe2x80x9coperativexe2x80x9d diameter which is equal to or slightly larger than the diameter of the blood vessel or other anatomical passageway in which the stent is to be implanted. When radially expanded to such operative diameter, the stent will typically become released from the delivery catheter and embedded or engaged to the surrounding wall of the blood vessel or other anatomical passageway.
Some stents are covered with tubular sleeves, in which case they are typically referred to as a xe2x80x9cstented graftxe2x80x9d.
In general, stents and stented grafts fall into two major categoriesxe2x80x94a) self-expanding and b) pressure-expandable. Those of the self-expanding variety may be formed of resilient or shape memory material (e.g., spring steel or nitinol(trademark)) which is capable of self-expanding from its first (radially compact) diameter to its second (operative) diameter without the exertion of outwardly-directed force against the stent or stented graft. Examples of such self-expanding stents and stented grafts are set forth in U.S. Pat. No. 4,655,771 (Wallsten, et al); U.S. Pat. No. 4,954,126 (Wallsten); U.S. Pat. No. 5,061,275 (Wallsten, et al); U.S. Pat. No. 4,580,568 (Gianturco); U.S. Pat. No. 4,830,003 (Wolf, et al); U.S. Pat. No. 5,035,706 (Gianturco, et al); U.S. Pat. No. 5,330,400 (Song) and U.S. Pat. No. 5,354,308 (Simon, et al) and Foreign Patent Publication Nos. WO94 12136; WO92 06734 and EPA183372. Those of the pressure-expandable (i.e., xe2x80x9cpassive expandablexe2x80x9d) variety may be formed of plastically deformable material (e.g., stainless steel) which is initially formed in its first (radially compact) diameter and remains stable in such first diameter until such time of outwardly directed pressure is exerted upon the stent or stented graft to cause radial expansion and resultant plastic deformation of the stent or stented graft, to its second (operative) diameter. Examples of such pressure-expandable stents and stented grafts are set forth in U.S. Pat. No. No. 5,135,536 (Hillstead); U.S. Pat. No. 5,161,547 (Tower); U.S. Pat. No. 5,292,331 (Boneau); U.S. Pat. No. 5,304,200 (Spaulding); U.S. Pat. No. 4,733,665 (Palmaz); U.S. Pat. No. 5,282,823 (Schwartz, et al); U.S. Pat. No. 4,776,337 (Palmaz); and U.S. Pat. No. 5,403,341 (Solar) and Foreign Patent Publication Nos. EPA480667; and W095 08966.
In many applications, careful positioning and firm implantation of the stent or stented graft is critical to the successful treatment of the underlying medical problem. In this regard, the delivery catheter which is utilized to accomplish the positioning and implantation of the stent or stented graft is an important aspect of the overall system. Various types of delivery catheters for stents and stented grafts have been previously known, including those described in U.S. Pat. No. 4,665,918 (Garza, et al); U.S. Pat. No. 4,733,665 (Palmaz); U.S. Pat. No. 4,739,762 (Palmaz); U.S. Pat. No. 4,762,125 (Leiman, et al); U.S. Pat. No. 776,337 (Palmaz); U.S. Pat. No. 4,838,269 (Robinson, et al); U.S. Pat. No. 4,994,071 (MacGregor); U.S. Pat. No. 5,037,427 (Harada, et al); U.S. Pat. No. 5,089,005 (Harada); U.S. Pat. No. 5,102,417 (Palmaz); U.S. Pat. No. 5,108,416 (Ryan, et al); U.S. Pat. No. 5,141,498 (Christian); U.S. Pat. No. 5,181,920 (Mueller, et al); U.S. Pat. No. 5,195,984 (Schatz); U.S. Pat. No. 5,201,901 (Harada, et al); U.S. Pat. No. 5,269,763 (Boehmer, et al); U.S. Pat. No. 5,275,622 (Lazarus, et al); U.S. Pat. No. 5,290,295 (Querals, et al); U.S. Pat. No. 5,306,294 (Winston, et al); U.S. Pat. No. 5,318,588 (Horzewski, et al); U.S. Pat. No. 5,344,426 (Lau, et al); U.S. Pat. No. 5,350,363 (Goode, et al); U.S. Pat. No. 5,360,401 (Turnland); U.S. Pat. No. 5,391,172 (Williams, et al); U.S. Pat. No. 5,397,345 (Lazarus); U.S. Pat. No. 5,405,380 (Gianotti, et al); U.S. Pat. No. 5,443,452 (Hart, et al); U.S. Pat. No. 5,453,090 (Martinez, et al); U.S. Pat. No. 5,456,284 (Ryan, et al); and U.S. Pat. No. 5,456,694 (Marin, et al) and Foreign Patent Publication Nos. EP-0308-815-A2; EP-0335-341-A1; EP-364-787-A; EP-0442-657-A2; EP-482976-A; EP-0505-686-A1; EP-0611-556-A1; EP-0638-290-A1; W094 15549; W095 01761; GB2196-857-A; DE3042-229; and DE3737-121-A. Generally, the attributes which are desirable of any delivery catheter which is to be used for placement and implantation of stents or stented grafts, are as follows:
a) maintain minimal diameter during insertion to avoid unnecessary trauma and/or difficulty of placement;
b) include radiopaque markings at appropriate locations to facilitate precise visualization and positioning of the delivery catheter to ensure that the stent or stented graft is implanted at the desired location;
c) reliable and reproducible expansion of the stent or stented graft to its full operative diameter, without regional or localized variations in the degree or completeness of such expansion;
d) reliable and reproducible disengagement or release of the stent or stented graft from the catheter body;
e) ability to withdraw and remove the delivery catheter without disturbing the newly implanted stent or stented graft; and,
f) ability to easily check for leakage of biological fluid (e.g., blood) outside of a stented graft (i.e., an xe2x80x9cendoleakxe2x80x9d) after the stented graft has been delivered and implanted within a body lumen.
None of the previously-known delivery catheter systems have been clearly optimal for all types of stents and stented grafts. Accordingly, there remains a need in the art for a design and development of improved delivery catheter systems for at least some types of stents and stented grafts.
The present invention provides a method and system for implanting a tubular endoluminal prosthesis (e.g., a stent or stented graft) within a body lumen (e.g., artery, vein, gastrointestinal tract, ducts of the biliary tree, urinary tract, reproductive tract, or other endocrine or exocrine ducts, etc.) of a mammal. The system of the present invention includes a) a delivery catheter; b) an introducer assembly; and c) a dilator.
In accordance with the invention, there is provided a delivery catheter which is usable for introducing and implanting a radially expandable tubular endoluminal prosthesis within a duct of the body. The delivery catheter incorporates one or more of the following elements:
a) a portion of the catheter being formed of separate tubular members upon which opposite ends of a radially expandable balloon are mounted such that movement (e.g., longitudinal, rotational) movement of one of such members relative to the other will cause the balloon to be tightened (e.g., longitudinally drawn, rotatably twisted) to a taut configuration when the balloon is in its deflated state, thereby eliminating or minimizing loose or protrusive balloon material which may interfere with subsequent retraction and removal of the delivery catheter; and/or,
b) a non-tapered or minimally-tapered balloon which is usable to radially expand the tubular intraluminal prosthesis, said balloon being mounted on the body of the delivery catheter and comprising:
i) a substantially cylindrical sidewall which is disposed coaxially about the longitudinal axis of the delivery catheter,
ii) a proximal end wall which extends from the proximal end of the cylindrical sidewall to the outer surface of the catheter body; and
iii) a distal end wall which extends from the distal end of the cylindrical sidewall to the outer surface of the catheter body, said proximal and distal end walls being disposed at angles which are no more than ten (10) degrees from perpendicular to the longitudinal axis of the catheter body; and/or,
c) a loader assembly for facilitating introduction of the distal portion of the catheter and a radially-compact intraluminal prosthesis mounted thereon, into a tubular introducer. Such loader assembly may comprise a tubular sheath which is advancable over the radially compact intraluminal prosthesis mounted on the catheter body, and which is directly engageable to the proximal end of an introducer so as to facilitate subsequent advancement in introduction of the radially compact intraluminal prosthesis into the lumen of the introducer; and/or,
d) one or more radiographic contrast medium outflow apertures in communication with a radiographic contrast medium infusion lumen extending longitudinally through the catheter, said outflow aperture(s) being positioned on the catheter at a location whereby radiographic contrast medium may be infused through the lumen and out of the outflow aperture(s) into the body lumen wherein the endoluminal prosthesis has been implanted, at a location upstream of the endoluminal prosthesis, such that said radiographic contrast medium will migrate outside of the endoluminal prosthesis if endoleak(s) exist whereby endogenous fluid flowing through the body lumen is seeping or leaking around the endoluminal prosthesis due to inadequate or imperfect implantation and abutment of the endoluminal prosthesis against the body lumen in which it is implanted.
Further in accordance with the invention, there is provided an introducer assembly comprising an elongate tubular introducer sheath having one or more of the following elements:
a) an embedded radiopaque marker which comprises a ring or segment of radiopaque material which has been melted or otherwise embedded within the wall of the introducer sheath so as to be fully surrounded or encapsulated by the material of the introducer sheath, while remaining visible by radiographic means; and/or,
b) a valving assembly (e.g., xe2x80x9cvalving headxe2x80x9d) mounted on the introducer sheath in alignment with the lumen of the introducer sheath, said valving assembly comprising:
i) a hemostatic valve (e.g., a xe2x80x9cduck bullxe2x80x9d check valve) positioned in longitudinal alignment with said introducer lumen, said hemostatic valve comprising a pliable hemostatic valve body having a self-sealing passageway formed therein, said self-sealing passageway being biased to a closed configuration whereby blood is substantially blocked from backflowing in the proximal direction through said hemostatic valve when no elongate member is inserted through the introducer lumen, said self-sealing passageway being enlargeable to permit first and second elongate members of said first and second outer diameters to pass therethrough;
ii) a first sealing valve (e.g., an elastomeric valve having a cross-slit opening formed therein) in longitudinal alignment with said hemostatic valve, said first sealing valve comprising a pliable first sealing valve body having a first sealing valve opening formed therein, said first sealing valve opening being initially of a first diameter which will allow said first elongate member to pass therethrough, and enlargeable to a second diameter which will allow said second elongate member to pass therethrough in sealing contact with said first sealing valve body such that blood will be prevented from backflowing in the proximal direction through said first sealing valve while said second elongate member is inserted therethrough; and,
iii) a second sealing valve (e.g., an elastomeric disc. valve having an annular opening formed therein) in longitudinal alignment with said first sealing valve and said hemostatic valve, said second sealing valve comprising a pliable second sealing valve body having a second sealing valve opening formed therein, said second sealing valve opening being initially of a first diameter which will allow said first elongate member to pass therethrough in sealing contact with said second sealing valve body such that blood will be prevented from backflowing in the proximal direction through said second sealing valve when said first elongate member is inserted therethrough, and being enlargeable to at least said second diameter to allow said second elongate member to pass therethrough.
In embodiments wherein the introducer sheath incorporates the valving assembly mounted on the introducer sheath, such valving assembly may be positioned on the proximal end of the introducer sheath and may be volitionally detachable therefrom so as to permit interchangeability of the introducer sheath without requiring the use of multiple valving assemblies. Also, the proximal end of the introducer sheath (or of the valving assembly if positioned thereon) may be provided with threads or other engagement members to permit a loader assembly to be positively engaged (e.g., locked) thereto, thereby facilitating smooth advancement of a delivery catheter having an endoluminal prosthesis mounted thereon into and through the lumen of the introducer sheath.
Still further in accordance with the invention, there is provided a dilator which is insertable through the lumen of an introducer sheath to dilate an intersticial puncture tract to the diameter of the introducer sheath, said dilator comprising an outer tube formed of a first material and an inner cylindrical member formed of a second material which is softer than the first material. A distal portion of the outer tubular member is removed and the adjacent material of the inner cylindrical member is tapered by way of a radio frequency process or machining process, thereby exposing a tapered segment of the relatively soft inner cylindrical member at the distal end of the dilator, while allowing the proximal portion of the dilator to remain sheathed by the relatively hard outer tubular member. A guidewire lumen may extend longitudinally through the inner cylindrical member to permit the dilator to be advanced over a pre-inserted guidewire.
When constructed in this manner, the distal end of the dilator is sufficiently soft to be advanced through tortuous anatomical structure such as blood vessels without causing undue trauma or perforation thereof, while the proximal portion of the dilator is sufficiently rigid to perform an anatomy-straightening function whereby pliable anatomical structures (e.g., blood vessels) wherein the dilator is advanced will be urged or brought toward linear alignment with one another by virtue of advancement of the relatively rigid proximal portion of the dilator therethrough. In this manner, the dilator may facilitate ease of advancement of the distal end of the introducer to a desired location (e.g, within the distal portion of the abdominal aorta) even though it must pass through relatively tortuous anatomical passageways (e.g., the femoral and iliac arteries).
In accordance of the methodology of the present invention, the above-described dilator is initially insertable through the lumen of the introducer sheath such that the pliable, tapered distal portion of the dilator protrudes out of and beyond the distal end of the introducer sheath. Thereafter, the introducer sheath/dilator combination is insertable through an intersticial tract into a blood vessel or other body lumen such that the relatively soft distal portion of the dilator and the distal end of the introducer are located within the body lumen. Thereafter, the dilator is extracted and removed from the introducer sheath, and the valving assembly of the introducer sheath (if present) will prevent backflow or leakage of blood or other body fluid out of the proximal end of the introducer sheath. Thereafter, the loader assembly of the delivery catheter (if present) is engageable with the proximal end of the introducer sheath and the delivery catheter, having the radially expandable endoluminal prosthesis mounted thereon, is advanced through the introducer sheath until the balloon and accompanying endoluminal prosthesis are located at the desired implantation site within the body lumen. Thereafter, the balloon is inflated to cause radial expansion and implantation of the endoluminal prosthesis. Thereafter, the balloon is deflated and the catheter assembly is longitudinally telescoped or elongated (if such capability exists) to draw the deflated balloon to a taut configuration such that the delivery catheter and deflated balloon may be extracted and removed without fouling or snagging the radially expanded and implanted endoluminal prosthesis.
Further objects and advantages of the present invention will become apparent to those skilled in the art upon reading and understanding of the following detailed description and accompanying drawings.